/**
  * Get collection of users by the specified role.
  *
  * @param  string $role
  * @return \Illuminate\Support\Collection
  */
 public function getAllByRole($role = null)
 {
     $users = User::where('role', '=', $role)->get();
     if ($users->count()) {
         $users = $users->keyBy('id');
         $ids = array_keys($users->all());
         $accounts = $this->getBatchedCollection($ids);
         foreach ($accounts as $account) {
             $account = $this->appendRole($account, $users[$account->id]->role);
         }
         return collect($accounts);
     }
     return $users;
 }